The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
An axle assembly for a motor vehicle includes internal moving parts that generate heat during operation of the axle assembly. It is desirable that heat generated in the axle assembly during its operation be controlled, as excessive heat could cause premature breakdown of the lubricant within the axle assembly, which in turn can reduce the life of the internal parts.
Some conventional axle assemblies employ the housing of the axle assembly to reject heat. In this regard, lubricant within the axle assembly is typically splashed by a ring gear onto the various gears within the axle assembly and heat from the gears is absorbed by the lubricant. The heated lubricant may collect in a sump, where some of the heat is transmitted to the housing. The housing can in turn reject the heat to the surrounding air, particularly the portion of the housing proximate to the sump. In addition, the heated lubricant collecting in the sump can be splashed onto the housing in areas outside of the sump. Heat from the splashed lubricant is transmitted to the housing of the axle assembly, which can then reject heat to the surrounding air.
We have found, however, that the ring gear does not always sufficiently circulate all of the lubricant in the sump, particularly the portion of the lubricant in the sump that is disposed in areas of the sump that are more distant from the ring gear, such as the portion of the lubricant near the differential side bearings. We have further found that the geometry of the various components that define the shape of the sump may inhibit fluid exchange in particular areas of the sump.